BY POPULAR DEMAND: HUBBLE OBSERVES HORSEHEAD NEBULA

Rising from a sea
of dust and gas like a giant seahorse, the Horsehead
nebula is one of the most photographed objects in
the sky. NASA's Hubble Space Telescope took a close-up
look at this heavenly icon, revealing the cloud's
intricate structure. This detailed view of the horse's
head is being released to celebrate the orbiting
observatory's eleventh anniversary. Produced by
the Hubble Heritage Project, this picture is a testament
to the Horsehead's popularity. Internet voters selected
this object for the orbiting telescope to view.

The Horsehead,
also known as Barnard 33, is a cold, dark cloud
of gas and dust, silhouetted against the bright
nebula, IC 434. The bright area at the top left
edge is a young star still embedded in its nursery
of gas and dust. But radiation from this hot star
is eroding the stellar nursery. The top of the nebula
also is being sculpted by radiation from a massive
star located out of Hubble's field of view.

Only by chance
does the nebula roughly resemble the head of a horse.
Its unusual shape was first discovered on a photographic
plate in the late 1800s. Located in the constellation
Orion, the Horsehead is a cousin of the famous pillars
of dust and gas known as the Eagle nebula. Both
tower-like nebulas are cocoons of young stars.

The Horsehead nebula
lies just south of the bright star Zeta Orionis,
which is easily visible to the unaided eye as the
left-hand star in the line of three that form Orion's
Belt. Amateur astronomers often use the Horsehead
as a test of their observing skills; it is known
as one of the more difficult objects to see visually
in an amateur-sized telescope.

The magnificent
extent of the Horsehead is best appreciated in a
new wide-field image of the nebula being released
today by the National Optical Astronomy Observatory,
taken by Travis Rector with the National Science
Foundation's 0.9 meter telescope at Kitt Peak National
Observatory near Tucson, AZ.

This popular celestial
target was the clear winner among more than 5,000
Internet voters, who were asked last year to select
an astronomical target for the Hubble telescope
to observe. The voters included students, teachers,
and professional and amateur astronomers.

This 11th anniversary
release image was composed by the Hubble Heritage
Team, which superimposed Hubble data onto ground-based
data (limited to small triangular regions around
the outer edge of the image). Ground-based image
courtesy of Nigel A. Sharp (NOAO/AURA/NSF) taken
at the 0.9-meter telescope on Kitt Peak.